Posted by: Manager / Associate Curator | September 18, 2016

Hill 70 & Cornwall’s Deadly Mustard Gas Plant


What does a largely hidden and vacant area smack in the middle of a Cornwall residential subdivision, a small park in rural North Dundas and a lesser-known World War I battle in France have in common?

The small rural community of Mountain in North Dundas has no mountain, but is named after Jacob Mountain, the first Anglican Bishop of Quebec. The former Good Shepherd Anglican Church in Cornwall was also known as Mountain Memorial – named after the same man.

A short distance from County Road 43, at 10481 Clark Road stands the entrance to the very unassuming Mountain Memorial Park. The park contains a hockey rink, a well-lit soccer field and clubhouse, a Battle of Hill 70 Memorial and a children’s play structure.


The Memorial professes to be the only one of its kind here in Canada, commemorating an important Canadian win against German aggression north of Lens, France. The short-lived battle between Canadian and German troupes in August of 1917 at this very strategic location forced the Germans to divert their attention away from Allied Troupes nearby. Both sides suffered high casualties (including 8,677 Canadians), but the Canadians largely succeeded in attaining their goal.


Former $3M Stormont Chemicals Limited plant – close to 50 buildings at its peak

During the battle, both sides made extensive use of poison gas; the Germans used a shell containing a blistering sulphur mustard. Due to concern that the use of such chemical warfare might escalate during the Second World War, a top-secret $3,000,000 chemical warfare factory was established here in Cornwall. In 1943 Stormont Chemicals Limited occupied nearly 50 buildings on 308.5 acres of land expropriated the year prior from three then Cornwall Township farms to produce a variety of warfare chemicals, including mustard gas should there be a need to retaliate against the Germans. It didn’t happen. 280 people were employed at this site protected by armed guards. The land is seldom mentioned today and sits hidden in plain view, west of Wallrich Avenue.

Drums awaiting "disposal"

Drums awaiting “disposal”

In January and February of 1946 10,000 unneeded drums of stored mustard gas (2,800 tonnes) were loaded onto 187 CNR box cars for a 900 mile journey to be “buried at sea” onboard a 400-foot long barge 40 miles south of Sable Island, southeast of Halifax at a depth of 600 fathoms. The dump location is 42 degrees, 50 minutes north by 60 degrees, 12 minutes west. Each of the five weekly shipments was accompanied by 20 armed guards and two technical directors, all of whom had advanced training in gas handling. An estimated 453,000 tonnes of chemical weapons are now lying at the bottom of the world’s oceans.

Between April and May 2007, as part of its Warfare Agent Disposal (WAD) Project, DND conducted an environmental site assessment at the facility at 540 Wallrich Avenue (until recently operating as Sensient Flavors) and concluded that there is no evidence of the presence of mustard agent or its by-products at the site.

The primary thread tying all of this together is our freedom which was purchased at such a great price … Lest we Forget, Lest we Forget. Perhaps Cornwall needs a relevant monument or a full site remediation and a reclaiming of this prime piece of real estate.

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